


Three-Sync

by SoloShikigami



Series: Heat Sync [2]
Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap, CEO, M/M, Multi, Office Sex, Threesome, Threesome - M/M/M, Underswap Papyrus, Undertail, heat - Freeform, sanswich
Language: English
Status: Completed
Published: 2016-06-28
Updated: 2016-06-28
Packaged: 2018-07-18 19:19:44
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,213
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7327084
Author URL: https://archiveofourown.org/users/SoloShikigami/pseuds/SoloShikigami
Summary: <blockquote class="userstuff">
              <p>The CEO of Snodynamics is noticing his assistant is having a bad time. So is the assistant from S.W.A.P. Corp. What is a boss to do when his assistants needs assistance?</p>
            </blockquote>





	Three-Sync

**Author's Note:**

  * For [PurrfecktlySinful](https://archiveofourown.org/users/PurrfecktlySinful/gifts).



> I told you guys; hope you like Sanswiches XD

            Swap paced in the meeting room, really, really wishing that he could smoke but he had promised his boss that he would only resort to cigarettes on the weekends. Sans was not the kind of boss that you would ever go back on a promise on. He thought of calling Sans to explain, hoping that he would have some mercy in the situation, but the problem was that he knew he was going through heat, too.

            "God damn fucking monster biology," he growled, rubbing his face with both hands.

\----------

            Sans shifted uncomfortably at his desk as he looking through the mountain of papers before him. His suit jacket was tossed haphazardly onto the chair next to his desk, his undone tie over his shoulder, his sleeves rolled up, top two buttons of his shirt undone, and he even slipped off his shoes. He glanced up at the thermostat which read 72 degrees.

            "Still too hot," Sans muttered, pushing some of the papers aside so he could slump over his desk with a pathetic whimper. He was thankful no one was around to hear him.

\--------

            Papyrus took a sip of his coffee with a worried look as he watched the security monitors that his friend Alphys was kind enough to install. He watched with concern as Swap paced, and with sympathy at Sans' slumped form.

            The CEO of Snodynamics Inc. was afraid that this would happen; considering the length of the project as well as the close proximity of the six skeletons working together, the end result he was seeing was becoming inevitable.

            "Right. I will have to fix this," Papyrus said with certain resolve.

\----------

            Sans was annoyed that Papyrus was making him work with Swap - generally he liked the guy, they shared a love of napping and slacking off, but today just was not the day.

            Especially when they were stuck in one of those meeting rooms - there were no windows, which made Sans claustrophobic, and it was always too stuffy, and they had to keep the door shut.

            Well, at least Swap seemed to be just as on edge to be at work as Sans was. The taller skeleton had been jumpy all morning.

            "What's up with you today?" Sans muttered.

            "Nothing," Swap said quickly. "Why? What's up with you? You seem a little irritated."

            "It's too hot in this damn place!"

            Swap stared at Sans, who was looking a little shocked by his own outburst. He had yelled. Usually Sans would deal with anger and rage by speaking softly and staring people down, he never had to raise his voice.

            But now he looked over at Swap and a wave of shame washed over him. Swap looked worried, concerned, maybe even scared. Sans definitely didn't want to see Swap scared, and definitely did not want him to be scared of him.

            "Hey, I'm sorry," Sans murmured. "It's, uh, been a rough week."

            "Psh, tell me about it," Papyrus said, sounding relaxed but his body still held tension.

            They looked at each other. Usually this would be the time where they would share an understanding smile, maybe crack a joke, and get back to work.

            Not this time.

            Sans noticed that faint wisps of orange were swirling in Swap's eyes; not enough to actually do something, and it was likely something most humans wouldn't have even picked up on.

            Likewise, Swap was noticing a bit of blue magic very lightly moving in Sans' eyes, a little stronger in the left than the right. He was so intrigued by it that he didn't notice how close they were until those eyes closed just as there was a soft **_clack!_** of bone against bone as Sans kissed his jaw.

            Swap leapt back, nearly tripping over one of the chairs surrounding the table. His hand flew up to where they had made contact and just stared.

            Sans watched him carefully; he was only slightly startled by Swap's violent reaction. But he wasn't running, there was no protest, a little lost for words or actions and his eyes displayed a lovely mix of confusion and want.

            Lifting his hands in a peaceful, placating manner, Sans took slow steps towards to the taller skeleton. With the sudden outburst, more signs of their heat became present - the magic swirling in their eyes grew brighter, the temperature of the room seemed to go up a few more degrees, and their signature scents were becoming unmistakable; a scent akin to honeysuckle and rain radiated off Swap while something vaguely like pine and juniper came from Sans.

            "Swap?" Sans murmured as he approached, still slow and unthreatening but sure in his actions.

            Swap started shaking - he really was resisting his heat as hard as he could. The shaking only increased as Sans put a hand on his chest; even though he already felt like he was on fire, Sans' hand was still warm through his shirt.

            Sans pressed forward more, leaning up on his toes to place a quick kiss under Swap's jaw. He lifted his hands and started to slowly unbutton his pale orange dress shirt.    Meanwhile, Swap stared down at him, part of him wanting to push him away and another wanted to shove him against the nearest wall and have his way with the smaller skeleton.

            Instead he choked on a sob as he struggled with himself.

            Sans stopped immediately at the noise, only one button undone. "Just tell me what you want," he said encouragingly, fingers shaking as he held off.

            Swap continued to stare, his mouth opening and closing as if he wanted to speak but nothing came out.

            A hand settled on his shoulder from behind, forcing a surprised cry from his dry mouth.

            "I think you are over-worked," a gentle voice said in his ear.

            Swap's entire body went rigid, and one could almost hear the creaking of bones as he swiveled his head to glance over his shoulder to find himself staring slightly up into the face of Snodynamics CEO.

            Papyrus was a couple of inches taller than Swap, he didn't have any sharpened teeth, and his face was always smiling - this time it was one of concern, maybe pity?

            "What?" Swap stammered.

            "I believe you and Sans are synced," Papyrus said.

            "Synced?"

            Papyrus chuckled, his other hand resting on Swap's other shoulder, squeezing them a little.

            "Now, now, do not play stupid. The way I see it is that I have two assistants who are in need of assistance. I, of course, am only assuming that you may not have someone to aid you in your time of need. I have already made provisions to help Sans, it would be a bit rude to not extend the same courtesy to you."

           Swap blinked up at the taller skeleton; he had the same talent as his own boss when it came to reading people, but no one needed such skills to see and hear the sincerity, concern, and caring that Papyrus tended to always carry in his voice.

            The flabbergasted skeleton was reminded there was someone else when he felt a slight pawing at his chest. He looked down to see Sans giving him a pleading look.

            ' _Fucking hell, it is true; he's in heat, same as me,_ ' Swap thought.

            With Sans fucking **_staring_** at him like that and Papyrus solid at his back, gentle hands rubbing his shoulders, Swap's wall of resistance fell and he nodded.

            It was like Sans had been tethered by an invisible rope that finally got cut and he launched himself into Swap at the same time Papyrus's arms wrapped protectively around his waist. Swap had no choice but to go with being pulled back at the same time Sans pushed forward.

            Papyrus had a chair at the ready and had dropped into it with Swap now sitting in his lap. His hands trailed over Swap's arms, earning him a shudder before he pressed his fingers into his ribs as he slid his hands to the buttons of his shirt to finish what Sans had started.

            Sans immediately pressed into him, touching Swap wherever he could as he overtook the other's mouth with his own, blue tongue coming out to lick experimentally.  As soon as the top buttons were undone, Sans dove in to lick at the long neck and clavicles.

            Swap moaned, lifting his hands in an attempt to do something but one just dropped on Sans' shoulder while the other gripped onto Papyrus' arm. He couldn't tell whose fingers danced over his ribs as they were slowly exposed. There was a gentle tug on his chin as his face was turned and a pale orange tongue traced around his mouth, asking for entrance.

            Sans pulled back from lavishing attention on Swap's neck to watch for a little. He smiled as Swap relaxed more and his boss was definitely enjoying himself as well. Sans leaned up and nuzzled the side of Papyrus' face, who broke the kiss with Swap for a moment to give him some attention too.

            Normally, Swap would have been grateful for the moment to catch his breath, but the burning of his heat made him miss the contact immediately. After a moment he leaned forward and started licking at Sans' neck, pulling his shirt from his pants, completely heedless of the murmured conversation going on over his shoulder.

            "…Sans."

            Swap heard the name whispered and it made something inside him freeze. With a shudder and a pained groan, he slid off Papyrus' lap and onto the floor, his whole body shaking; he could barely pull his knees to his chest.

            "Hey," Sans broke off the kiss and knelt on the floor in front of Swap. "Buddy?"

            Papyrus frowned, pushing the chair away and joining the other two on the floor. He switched positions with Sans, who looked lost and confused as well as concerned, but he was likely in no mind set to be able to help much. Papyrus was the only one not in heat and had a clear head.

            "Talk to me," Papyrus said gently, placing his hands on Swap's patella’s.

            A strange, strangled noise came from Swap, who didn't lift his head.

            "It burns," he finally forced out after a moment. "I want to, but can't, he, Sans in heat too, I should-"

            Papyrus listened to every pain-laced word and his mind started putting two and two together. He knew he didn't mean his Sans.

            "Look at me," Papyrus said, gentle but demanding.

            Swap slowly looked up, and when he could, Papyrus reached forward and slid a hand under his jaw to make sure he would continue to look at him.

            "I'm not here to force you. I'm here to help you. You do what you feel you should but I don't want to see you hurt.”

            "Papyrus," Sans said softly, voice strained as he leaned his head on Papyrus' back.

            "I know, Sans, just a moment," Papyrus promised. He turned back to Swap. “What would Sans say or do if he were here, if he knew of your situation?"

            After a moment, Papyrus pulled away, reaching back to tap Sans on the leg and he turned to give him a little attention while Swap thought.

            What _would_ his Sans say? Swap frowned a little, the question powerful enough in his mind to push away the effects of his heat to think clearly.

            His Sans, with his big blue eyes, ever-present encouraging grin, happy disposition and positive attitude; his Sans, who he was certain would do anything to make those around him happy. Sans would be devastated to hear that Swap had been holding out on his heat all alone.

            Swap flinched when he remembered that he was forced to leave Sans to deal with the CEO of Edge Inc. but certainly Sans could handle him.

            What if they synced, too? Would Swap deny him the relief if it was offered to him?

            Of course he wouldn't.

            A small moan brought back his attention and his heat returned in full force upon seeing the pair before him; Sans was sitting in Papyrus' lap, his shirt unbuttoned, one side falling off his shoulder, Papyrus nibbling at his neck while his thumbs were rubbing circles on his hipbones, which were only slightly peeking out of the waist of his pants.

            The smaller skeleton noticed that Swap was back with them and he smiled.

            "You okay over there?" he asked.

            Swap nodded slowly. Sans gave Papyrus a small tap on his chest and he looked up. Sans crawled out of his lap towards Swap.

            "So, what's the verdict?" Sans asked.

            "I-I'll s-st-stay," Swap stammered.

            Sans chuckled. "Good."

            He crawled forward another few inches, Swap straightened his legs and opened them to allow Sans room to crawl between them. Sans came off his hands to cradle Swaps’ face as he kissed him.

            Papyrus leaned back a little to watch with a smile. It took a few moments but Swap’s hands were roaming everywhere on Sans that he could. Sans' put one hand on Swap's shoulder to keep himself steady, his other hand started trailing along the inside of Swap's leg. He pressed his hand to Swap's pelvis, feeling the magic beginning to gather.

            Sans smirked, breaking the kiss to grin at Swap before he started to lick down his neck and ribcage while both of his hands were occupied between his legs. Swap put his hands behind him to keep himself steady as his breath started to come out in pants and pathetic whines.

            Papyrus moved forward, rubbing a hand encouragingly down Sans' back before reaching up to catch Swap's jaw again.

            "Shh, shh," Papyrus murmured. "We're going to take good care of you. I promise I'll make it all better."

            "O-okay," Swap said, his breath hitching as Sans pressed a palm to his crotch.

            Papyrus smiled and leaned in to kiss him gently, slowly opening his mouth to twine their tongues together.

            Sans nudged Swap to lift his hips so he could slide down his pants, and he was thrilled when he complied. He shoved them and the brown dress those off the long limbs before crawling back to nuzzle the erection that was formerly trapped beneath the khaki material.

            Papyrus couldn't help smiling a little as Swap began to let out little moans as they kissed, knowing Sans was responsible for them. He curled a hand around Swap's skull to keep him still as he pressed in deeper, starting to take in his reactions to Sans motions below.

            Sans slowly licked up the orange shaft, tracing his tongue just under the ridge below the head before running his tongue down the other side. He repeated the motion a few times, feeling Swap twitch and groan at the teasing touch.

            "Sans, don't be cruel," Papyrus admonished him when Swap let out a particularly needy cry.

            Without another word, he took all of Swap in at once, pressing his tongue hard on the under side so it pressed against the roof of his mouth before he slowly pulled away, his teeth scrapping along lightly. Swap kicked his legs uselessly, squirming under Sans' mouth. Sans swirled his tongue around the head of his cock before pulling off.

            "Mmm, more, please," Swap was barely able to gasp out.

            Sans was more than willing to oblige and immediately his head began to bob between his legs.

            After a few minutes, Papyrus started to get the feeling that Swap was close as his breath quickened and was tensing. Papyrus broke away from him and reached down to stroke Sans' back.

            "Not yet," he murmured in Sans' ear, placing a quick kiss on Swap's leg, making him twitch. "Your heat needs to be satisfied, too."

            Sans pulled off with a small gasp and a nod. He looked at Swap with a smile, shuffling forward on his knees, a hand reaching under the wet cock, looking for an entrance. He found it easily enough and gently twisted a finger into it.

            "Ahhh!" Swap cried, his head dropping back.

            Papyrus smirked and moved back further to settle himself behind Sans and began to take off his pants as well. Sans' magic already formed what Papyrus wanted and he reached down to stroke the pale blue cock, enjoying the solid appendage in his hands but enjoying the sigh of pleasure it brought out of Sans more. Feeling a little adventurous, he leaned down and ran his tongue between the fleshy mounds of magic.

            "Mmmmm, boss," Sans whined, wriggling his hips a little.

            "Should I stop?" Papyrus asked.

            "Fuck, no... Ack!"

            The sound of a slap echoed in the room.

            "Watch your language."

            Sans blushed and returned to fingering Swap, who had a strong blush forming on his face.

            "That was kind of hot," he murmured down to Sans.

            Sans pushed a second finger in, making Swap cry out again.

            "Not as hot as you look," Sans murmured so only he could hear, leaning up to kiss him. "And you'll probably look even hotter while I'm fucking you."

            The blush on Swap intensified as he shuddered.

            "You're never going to find out if you don't do it," Swap murmured, his voice borderline challenging.

            Sans smirked and leaned down to bite his neck. "All right then."

            Papyrus had heard some of the exchange and backed off to watch. Sans edged forward a little more, pulling on Swap's hips so he was a little closer, his arms unable to hold his weight so he dropped flat on the floor.

           Gripping his cock, he rubbed the head at Swap's hole, coating it with his pre-cum before he slowly slid inside.

            The moans that slipped from both of them were music to Papyrus' ears; the satisfied sound of a need being met. From his vantage point he couldn't see the look on Sans' face but he could only imagine that Swap mirrored it. His eyes were half-lidded, wisps of orange magic curling around his eye sockets, his mouth open as he panted breathy moans. Sans was still for a moment, enjoying the heat squeezing around him, and then started thrusting in a quick, shallow rhythm.

            Swap's hands gripped at the thin carpet below them, trying to find something to hold on to, but then thin fingers intertwined with his own. He glanced up to see Papyrus looking down at him with a loving smile as he held one hand.

            "It's all right," Papyrus said soothingly. "Here, this will make it feel real good."

            Papyrus guided Swap's hand so he was holding his femur up and then moved to the other side to do the same. This changed the angle slightly and Sans thrust in deeper, making them both moan pleasurably. Papyrus smiled to himself as he moved back behind Sans.

            "Feel good?" Sans grunted.

            "Uh, uh huh," Swap said between thrusts. "Please, more."

            Sans chuckled and started pulling out further and drove in harder, drawing loud cries from the tall skeleton below him.

            After a few moments, Sans felt a pair of warm hands caress his hips before gripping onto them firmly, a chest pressed into his back.

            "Slow down a little," Papyrus' voice purred into his ear.

            Sans obeyed with a grunt of annoyance and Swap let out a small cry of protest. A familiar sensation came from behind as Papyrus slowly penetrated Sans.

            "Ooooohhh, damn, Papyrus," Sans groaned, stilling as he was being filled.

            Another slap to his behind made him hiss.

            "Language."

            "Sorry."

            Swap's eyes had screwed shut at one point and after a few moments he opened them again and a new wave of heat flowed over him. Sans' eyes were rolled up slightly, his mouth was open, his tongue lolling out of one corner of his mouth, drooling a little. Behind him, Swap could see Papyrus' satisfied face as he buried himself into the small skeleton, which pushed Sans into him more.

            "Mmm, stars, you feel so good," Papyrus whispered in the side of Sans' skull.

            Sans only let out a small squeak in response.

            Papyrus chuckled, kissing the skull briefly before looking down at Swap. "Are you all right down there?"

            Swap swallowed hard and nodded.

            "That's great. Come on, Sans, let's show him a good time."

            Sans seemed to come back to himself and chuckled.

            Then they began moving.

            Swap couldn't help but wonder how often they had done this; the rhythm was perfect, the angle was hitting a spot inside Swap that was sending shock after pleasurable shock up his spine, and the sight of the two faces above him were just pushing him on.

            Papyrus was definitely enjoying himself; he was pleased to be aiding Swap and Sans, heats sucked, he loved being inside Sans and was immensely turned on by the noises and looks he was getting from Swap. He chuckled and bent down to kiss the back of Sans' neck.

            Sans was beginning to feel overwhelmed. Swap was warm and tight around him, Papyrus filling him from behind as he guided his thrusts, taking control so Sans could just feel it all happen.

            Papyrus could tell Sans was reaching his peak, he saw the blush on Swap's face deepening and was guessing he was getting close too.

            "Think we can make him come first?" Papyrus murmured.

            "Yeah," Sans agreed.

            "Wha-?" Swap started to ask, barely hearing their murmuring voices before he was cut off by Sans stroking his cock in time with their thrusts.

            "Come on, buddy, let it go, I know you want to," Sans said, smirking down at him.

            Another flush stole through Swap, his body felt over sensitive, and he wanted to cum and badly but something was still holding him back.

            Papyrus, once again, seemed to sense it and know exactly what to do.

            "Call him by his full name," he murmured to Sans.

            "Cum for us, Papyrus," Sans said to him in a husky voice.

            That did it. Swap shuddered at the sound of his name spoken in that tone of voice and he let out a cry as white spurted out, some of it staining his shirt and coating Sans' hand.

            "Good, good, just hang in there for a moment," Sans murmured.

            Papyrus slowed his thrusts, making Sans gasp and yank his head around to glare at him over his shoulder.

            "What the fuck are you doing?" Sans growled.

            Papyrus spanked him again, harder this time. "If you want to cum, you better watch your language."

            Sans whined. "Aw, come on, don't be like that."

            Papyrus gently rocked his hips into him. "No? You want it that badly?"

            "You know I do."

            "I don't have any idea what you could possibly mean."

            "Come on, Papyrus, please?"

            Papyrus pulled almost all the way out and shoved back in roughly, making both skeletons cry out.

            "Tell me what I want to hear, Sans," Papyrus whispered in his ear.

            "I'm so sorry for swearing. Please, Papyrus, I want to cum."

            Papyrus nuzzled the side of his skull. "Of course, my loyal assistant."

            He suddenly picked up the pace. Sans' broken cries became louder until finally his body was caught in a spasm, squeezing Papyrus and unloading a warm stream inside of Swap, who was still shaking from his own orgasm. Sans collapsed on top of him and Swap wrapped his arms around the smaller skeleton.

            "Hold him still, this won't take long," Papyrus murmured.

            Swap did what he was told, feeling the smaller body rocking against him as Papyrus came to his own completion, Swap felt Sans twitching pleasurably, and finally Papyrus sighed as he pulled out and moved next to them to put an arm around them both after kissing each of them.

            Sans then dropped his mouth on Swap’s, kissing him a little longer than Papyrus had.

            "Feeling better?" Sans asked.

            "Yeah, you?" Swap asked in return.

            Sans snickered. "After that? Yeah. Glad to know you two couldn't possibly be hungry, though."

            Swap's face contorted in confusion. "Why do you say that? What does this have anything to do with-"

            "DON'T!" Papyrus warned too late.

            "Because you both just had a Sans-wich."

            "I am spanking you harder next time," Papyrus growled.

            "Promise?"

            Swap stared at Sans and then broke into a laugh.

            "DON'T YOU ENCOURAGE HIM OR I WILL SPANK YOU TOO!"

\----------

            A monitor switched on and a figure watched as Papyrus, Sans, and Swap slowly disentangled themselves and began putting on and straightening their clothes.

           “Mind if I have a copy of the feed to this room for the past hour or two?” the figure asked the security guard.

            “You’re the boss, Mr. Gaster,” the guard said with a slight shake to his voice.

            The figure grinned around the toothpick in his mouth. “Excellent.”

            It took a few moments for the security guard to make the copy and put it on a spare flash drive of his.

           “There you are, sir,” the guard shifted uncomfortably on his feet, knowing exactly what that video contained.

            “Aww, you’re looking a little downtrodden, friend,” the figure placed a hand on his shoulder and stared intently into his eyes. “You will forget that this happened, that you saw me.”

            The guard’s facial features went slack. “Nothing here happened. I am a good guard.”

            The figure smiled and pat him on the shoulder. “Good boy.”

**Author's Note:**

> Hmm... who's sneaking around the security room?  
> Come visit me on [TUMBLR!](https://soloshikigami.tumblr.com/)


End file.
